Biotissue‐Inspired Anisotropic Carbon Fiber Composite Hydrogels for Logic Gates, Integrated Soft Actuators, and Sensors with Ultra‐High Sensitivity

Abstract

Natural biotissues like muscles, ligaments, and nerves have highly aligned structures, which play critical roles in directional signal transport, sensing, and actuation. Inspired by anisotropic biotissues, composite hydrogels with outstanding mechanical properties and conductivity are developed by compositing thermo-responsive poly (N-isopropylacrylamide) (PNIPAM) hydrogels with highly aligned carbon fibers (CFs). The anisotropic hydrogels show superior tensile strength (3.0 ± 0.3), modulus (74 ± 7.0 MPa), excellent electrical conductivity (≈670 S m −1 ), and ultra-high sensitivity (gauge factor up to 647) along CFs, with an anisotropic ratio (AR) up to 740 over those in perpendicular direction. The extremely high AR in conductivity (more than 400) produces high-level output in parallel direction and low-level output in perpendicular direction with a direct current (DC) power supply, which is used to fabricate AND and OR gates. Moreover, the composite hydrogels are converted into thermo-responsive actuators with CFs twisted before compositing with PNIPAM/clay network. The pre-twisted CF helices impart internal stress that drives reversible actuation of hydrogel helices upon thermo-stimulating. The actuation is self-sensed due to the extremely high sensitivity of the composite hydrogels. Such biomimetic anisotropic self-sensing hydrogel actuators resemble natural biotissues with both actuation and sensing capabilities, and have promise applications for artificial robotics.

MXene-Mediated Cellulose Conductive Hydrogel with Ultrastretchability and Self-Healing Ability

“…Thus, the pronunciation signal peaks of “Beginning” are classified as the syllables “Be” and “ginning”, respectively, and the pronunciation of “Ending” is also similar (Figure h). After recording more syllables and machine learning, this feature may enable potential speech recognition in future research. , Furthermore, the large-scale behaviors of humans were also accurately tracked by the R-MCB (Figure S21b, c, and d). In consideration of the excellent self-healing performance of the MCB hydrogel, the electromechanical response test of the R-MCB before cutting and after healing was conducted.…”

Carbon‐Based Radar Absorbing Materials toward Stealth Technologies

“…Due to these properties, CFs are widely used in many applications, including electromagnetic absorber materials. [84,85] In this regard, a significant amount of work has been performed on CF-reinforced polymer composites (CFRPs) and CF/magnetic nanoparticles.…”

Bionic ordered structured hydrogels: structure types, design strategies, optimization mechanism of mechanical properties and applications

“…4 Analysis of mechanical properties of various bionic ordered structured hydrogels and comparison with disordered structured hydrogels. According to the different strengths, Young's modulus and toughness values collected in Table 2, the (A) strength versus Young's modulus and (B) toughness versus Young's modulus of homogeneous lamellar structure (blue), 20,56,108,113,159,172 heterogeneous lamellar structure (green), 28,59 fasciculate structure (red), 44,77,114,151,174,175 gradient structure (yellow) 30,65,97 and disordered structure (purple) [180][181][182][183] hydrogels were compared by Ashby diagrams. The coordination of the strong layer and weak layer is akin to that of the strong and weak bond.…”